Ousted Ukrainian leader Viktor Yanukovych maintains he is still the country's legitimate president, saying he believes he will be able to return to Kiev soon.

"I remain not just the sole legitimate president of Ukraine but also commander-in-chief," he said in his first public appearance in over a week, in the southern Russian city of Rostov-on-Don.

"As soon as the circumstances allow - and I am sure there is not long to wait - I will without doubt return to Kiev."

In contrast to his lengthy press conference when he re-emerged in Russia, Mr Yanukovych, who was speaking Russian, gave only a seven-minute statement.

He then left the stage alone without taking questions.

He reaffirmed his belief that power in Kiev had been taken by a "band of ultra-nationalists and neo-fascists" and said that presidential elections planned in May would be "absolutely illegitimate and illegal".

Mr Yanukovych told the new pro-West authorities in Ukraine, who took over after he fled to Russia last month, that "sooner or later, most likely sooner" they would be held responsible for their actions.

"You will be made responsible for the suffering of the people. Ukraine is now going through a difficult time," he said.

He blamed them for the fact that Ukraine appears to be about to lose control of Crimea which is set to be claimed by Russia after a referendum next week.

"Your actions have led to the fact that Crimea is separating and the people of the south and east are demanding respect, even in the face of machine guns," he said.

"We will get through this trouble, the people who have been deceived by you will see this and the country will rise up and unify."

The upheaval in Ukraine has escalated into the biggest showdown between Russia and the West since the Cold War.

But Mr Yanukovych has been relegated to the sidelines since his overthrow and had not been seen publicly since a news conference on February 28.

At the time, he said the Crimea region should remain part of Ukraine but enjoy autonomy.

In his latest remarks, Mr Yanukovych seemed to hold out little hope for that, saying only that Crimea was "breaking away" from Ukraine and that his foes were to blame.

Referendum for Crimea to join Russia to be held on Sunday

Russia has taken control of Crimea - though it denies pro-Russian forces there answer to Moscow - and has threatened to send the armed forces into Ukraine if it deems it necessary to protect its citizens and other Russian speakers there.

Pro-Russian politicians who have taken over Crimea's government plan to stage a referendum on Sunday on making the region, which has an ethnic Russian majority, part of Russia - a move Western governments say is unacceptable.

In a precursor to the referendum, the local assembly approved a "declaration on the independence of the autonomous republic of Crimea and the city of Sevastopol" on Tuesday, with 78 out of 81 lawmakers present voting in favour.

The move by the parliament, which has been declared illegal by the new government in Kiev, appeared to be aimed at creating a legal framework for joining Russia as a sovereign state.

The United States and Poland began war games on Tuesday as Washington makes a gesture of support for its eastern NATO allies, but bad weather delayed naval manoeuvres with Romania and Bulgaria.

The US says both the air drills and its joint naval exercises in the Black Sea were planned before the crisis in Ukraine.

However, they send a message of resolve to NATO members nervous about Russia's intentions in its former Cold War backyard, along with separate reconnaissance flights over Poland and Romania near the Ukrainian border.

Officials from several Western countries have met in London to identify Russians who would be subject to asset freezes and travel bans.

Poland's prime minister Donald Tusk said European Union sanctions would begin on Monday, the day after the referendum in Crimea.

Meanwhile, pro-Kremlin militants ordered a suspension of all flights in or out of Crimea's main airport in Simferopol except those connecting to Moscow.

Militants have taken over air traffic control at the airport and a flight that took off from Kiev on Tuesday was forced to turn back to the capital after being refused permission to land.

A militia member, Ivan, who declined to give his surname, said the move was aimed at preventing activists from Kiev from coming to Crimea.